The present invention relates to a method and an apparatus for producing labels. In particular, the present invention relates to the production of a succession of self-adhesive labels carried on a release material.
In the packaging field there is a great demand for high quality pre-printed labels for labelling containers of various types. In order to facilitate the packaging and labelling of containers at a fast rate it is generally required that the labels to be attached to the containers be made available in a form in which they are easy to handle and easy to transfer onto the containers for which they are intended. In one convenient arrangement the labels are self-adhesive labels which are carried in series on a web of release material which is wound into a reel.
It is well known in the art to produce reels of self-adhesive labels carried on a release paper for transfer of the labels from the release paper to a container to be labelled.
One process for producing such labels is described in my company's British Patent No. 1420933. This patent describes a process for the production of a continuous reel of self-adhesive labels, wherein the labels are produced as separate flat sheets cut to finished size and stacked, the separate labels are then fed in succession from the stack onto the periphery of a drum and held thereon by vacuum means while being fed to an applicator by which they are coated individually on their reverse sides with a pressure-sensitive adhesive composition, the adhesive is dried by passing the labels through a hot air chamber extending around a substantial part of the periphery of the drum, and the labels are applied successively by their adhesive coated sides to a continuous web of release paper which moves against said drum and which is then reeled.
However this process has certain disadvantages in that it is difficult to produce a continuous reel of self-adhesive labels in which there is a regular gap between adjacent labels. Generally it is preferred to have a regular gap for ease of application of the labels to containers in a continuous labelling process. The reason for this difficulty is that it is not readily possible to place each successive label accurately onto the periphery of the rotating drum and then subsequently to transfer the labels accurately from the drum to the moving web of release paper to obtain a regular spacing between adjacent labels on the release paper. In addition, accurate alignment of the labels on the release paper can be difficult to achieve because of the difficulties mentioned above which are encountered when transferring the labels from the stack of labels to the release paper. This can result in some of the labels being skew relative to other labels on the reel of release paper. When the labels are subsequently applied to containers from the reel, any labels which are in a skew position on the reel of release paper are inevitably transferred in an out-of-true condition and are therefore mis-aligned on the container to which they are attached. This is unacceptable as it renders the product so labelled unattractive to the consumer.
A further disadvantage of this process is that after coating the reverse sides of the labels with pressure-sensitive adhesive, drying the adhesive and applying the labels by their adhesive coated sides to the continuous web of release paper, one frequently obtains surplus adhesive appearing around the periphery of the labels on the release paper. When the release paper is wound into a reel this surplus adhesive adheres to the back of the adjacent layer of release paper and can subsequently interfere with the unwinding of the reel and the application of the labels to containers to be labelled.
European Patent Specification No. 0098092 discloses a method and apparatus for producing labels which attempt to overcome these disadvantages by arranging for the peripheral portions of labels applied to a support web to be removed after the labels have been applied to the support web and before the labels are wound into a reel. While the method and apparatus disclosed in that specification did overcome those disadvantages, nevertheless it was necessary to adhere the labels to an intermediary support web. The requirement for a support web increases the cost of production of the self-adhesive labels.
It is an aim of the present invention to provide a method and apparatus for producing labels which does not require a support web to which individual labels are adhered, such as those support webs which are disclosed in those two specifications referred to above.